Pretty much anywhere people turn for information about diabetes, including here at Diabetes Self-Management, you’ll read about the importance of a healthy diet in helping both to prevent diabetes and to manage it once you have it. Many of the recommended dietary strategies come from leading health and medical organizations, including the American Diabetes Association.
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But what people eat is complex, so it can be hard to study the effects of diet on diabetes-related outcomes. One recent study, though, found a relationship between certain dietary patterns and the risk of certain health outcomes, including developing diabetes.
Fruits, vegetables tied to lower diabetes risk
Published in the journal Nutrition & Diabetes, the study looked at the dietary patterns and health outcomes of 1,432 participants ages 40 to 65 in Hangzhou, China. One of the first tasks of the researchers was to identify major dietary patterns among participants, since no single nutrient or food was the focus of the study.
Based on the participants’ reported food intake along with 21 predefined food groups, the researchers identified four major patterns named for the categories of food that dominated their diets: vegetables–fruits, rice–meat, seafood–eggs, and sweet–fast food.
The researchers took certain health-related measurements in participants, including insulin resistance, body-mass index (BMI, a measure of weight that takes height into account), and visceral fat area (a measure of belly fat). They also looked at how many participants received a diagnosis of diabetes (mostly type 2) as part of the study, based on an oral glucose tolerance test (OGTT). These were people who hadn’t previously received a diabetes diagnosis.
The researchers found that the sweet–fast food dietary pattern was associated with higher insulin resistance, while the vegetables–fruits pattern was associated with lower insulin resistance. In men, there was also a significant relationship between the two dietary patterns and visceral fat area, with significantly more visceral fat associated with the sweet–fast food pattern and less with the vegetables–fruits pattern.
There was no observed association between either insulin resistance or visceral fat area and the rice–meat or seafood–eggs dietary patterns.
After adjusting for factors that could affect diabetes risk, the researchers also found that being in the upper third of the fruits–vegetables dietary pattern was associated with a significantly lower risk of diabetes in both men and women. Men in this group were only 30% as likely to receive a diabetes diagnosis as the overall group, and women were only 28% as likely.
In contrast, men in the upper third of the sweet–fast food dietary pattern were much more likely to have diabetes, with a risk 2.58 times as high as the overall group. There was no significant association between diabetes risk and the rice–meat or seafood–eggs dietary patterns.
Limited lessons from study
It shouldn’t be surprising that eating more fruits and vegetables was associated with a lower diabetes risk, and that sweet foods and fast food were tied to a higher diabetes risk. But when it comes to other categories of food like seafood and eggs, this study didn’t offer much in the way of helpful results.
The researchers note that this study, like many others, didn’t find any benefits associated with eating more seafood, even though some studies have found that eating more fish may help protect against diabetes. The inconclusive results may be due to varying methods of preparing fish, with some people seeing a health benefit from healthy preparation methods and others seeing a harmful effect from unhealthy methods.
There were other limitations to this study, such as the fact that it followed a cross-sectional design — meaning that it divided participants into groups based on behaviors that they already followed. Because of this, it couldn’t establish any cause-and-effect relationships between dietary patterns and health outcomes — just associations. In other words, it’s theoretically possible that people who ate lots of fruits and vegetables also had other healthy behaviors that actually explain their lower risk of diabetes.
Of course, another major limitation is that the study is based on people in one city in China. Its results may not apply to other cities in China, let alone dietary patterns in other countries. Still, it’s an important reminder of the role that diet may play in insulin resistance, obesity and diabetes.